The aim of this study was to fabricate needle like-TiO2/polyrhodanine nanostructures by polymerizing rhodanine monomer on the TiO2 nanoparticles' surfaces and investigate their antibacterial activities. The structural, thermal, morphological, surface and electrical properties of non-covalently functionalized nanoparticles were characterized by using FTIR, XPS, elemental analysis, TGA, XRD, SEM-EDX, TEM, contact angle, and conductivity measurements. Characterization results confirmed the formation of needle like-TiO2/polyrhodanine (PRh) core/shell hybrid nanostructures. Alterations on the surface and electrokinetic properties of the materials were characterized by zeta ()-potential measurements with the presence of various salts and surfactants. The -potential of needle like-TiO2 was observed to increase from -7.6 mV to +28.4 mV after forming a core/shell needle like-TiO2/PRh nanocomposite structure and with the presence of cetyltrimethyl ammonium bromide (CTAB) surfactant. Thereby colloidally more stable dispersions were formed. Antibacterial properties of needle like-TiO2/PRh were also tested against Staphylococcus aureus, Klebsiella pneumoniae, and Escherichia coli by various methods and they showed good antibacterial activity. The highest killing efficiency was determined for needle like-TiO2/PRh against E. coli by colony-counting method as 0.95. TEM experiments also showed the immobilizations of the nanoparticles on E. coli and revealed the interactions between E. coli and the nanoparticles. (c) 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41554.